THe best way to gain consistantly high levels of HP for the Mk2 is to swap in a 7MGTE. If you find a somewhat solid engine you can drop it right in and have the whole project done for about $2000-$3000. From what I know the 7M is an extreamly well built motor, it truely is the best of the M series.
Ok I don't want to sound like a 7M hater but it is not the best of the M Series, not by a long shot a 5M or 6M is much closer to that statement here is why (My opinon based on alot of experiance and observation)
1.) 7M-GTE motor is notorious for blowing Head gaskets, this can be resolved by replacing the head gasket with a MHG (not cheap especially factored into your new JDM motor price but much easyier to do before you put the motor in the car and it eventually blows) The reason for HG blowing so easily is the rediculously small bore spacing of the 5-7M motors, due to displacement increases over the years.
2.) 7M-GTE is notorious for overheating, why becuase it still uses the same coolling passages designed for a non turbo engine, The intercooler piping travels right over the turbo on its way into the intake... , and the intercooler has a 4psi preasure drop accross and is also quite prone to heatsoak. Some of the coolant lines that eventually break due to rapid heating and cooling (side effect of turbo engine) are almost impossible to reach with the motor in the car.
3.) Oil starvation, again something the 7M-GTE is famous for. This usually leads to rod knock and the replacement of the crank and new bearings not a fun job. Oil starvation occurs more often (but certainly not exclusivly) in cars with rebuilt motors, usually attributed to shaved head or block lowering the ablility of the tesnsioner to propourly pickup the slack on the timing belt and it "skips" across the oil pump gear not turning it at a propour rate of speed.
A freind of mine now has rod knock for the third time on his 7M-GTE, this was with a replaced, Block, Crank and rebuilt head, new timing belt etc.
Also as a member of the Toronto Supra Club I see alot of MKIII's (The club is jokingly referd to as the MKIII club due to there sheer numbers). The reliablity of the car/motor becomes obvious as cars that are absent from the meet but owners there collecting information on his motor job or replacement. There are a few cars that consistanly arrive to the meets and work reliably, these cars have had rediculous amounts of money thrown at them, and then are not driven over 4500rpm.
Just to illustrate my point, my friend (mentioned earlier) and I are not mechanics but we can now remove the entire 7M-GTE
engine and transmission in only 3hrs.... I now regularly hear the reliability of the 7M compared to that of a 13B.
For both cost effectiveness and reliablility I would highly recomend a 6M motor, they pull hard, run well and don't suffer the issues as the 7M due to lack of boost. Put a header on it, some exhaust, and maybe those TRD cams mentioned in this forum and you'll be in the 14's at the track. if you don't want to do a motor swap clould also performe the same mods to a 5M and get respectable power.
6M's sell for around $4-500CDN in southern ontario and I imagine are readily availible in the states.
And hey what makes a sweeter sound than an NA MKII?
Carl